1. Field of the Invention
The present invention relates to a fuel cell formed by stacking a membrane electrode assembly and separators together upright in a horizontal direction. The membrane electrode assembly includes a pair electrodes and an electrolyte membrane interposed between the electrodes.
2. Description of the Related Art
For example, a solid polymer electrolyte fuel cell employs a solid polymer electrolyte membrane. The solid polymer electrolyte membrane is a polymer ion exchange membrane, and interposed between an anode and a cathode to form a membrane electrode assembly (MEA). The membrane electrode assembly and a pair of separators sandwiching the membrane electrode assembly make up a power generation cell (unit cell) for generating electricity. In use, typically, several tens to several hundreds of the power generation cells are stacked together to form a fuel cell stack, e.g., mounted in a vehicle.
In the fuel cell, so-called internal manifolds are often adopted for supplying a fuel gas and an oxygen-containing gas as reactant gases to the anode and the cathode of each of the stacked power generation cells.
The internal manifold includes reactant gas supply passages (fuel gas supply passage, oxygen-containing gas supply passage) and reactant gas discharge passages (fuel gas discharge passage, oxygen-containing gas discharge passage) extending through the power generation cells in the stacking direction. The reactant gas supply passages and the reactant gas discharge passages are connected respectively to inlets and outlets of reactant gas flow fields (fuel gas flow field, oxygen-containing gas flow field) for supplying the reactant gases along electrode surfaces.
In some cases, the recant gas supply passages and the reactant gas discharge passages may be connected to the reactant gas flow fields through connection channels each having a plurality of through holes for allowing the reactant gases to flow smoothly and uniformly.
In this regard, for example, as shown in FIG. 7, as disclosed in Japanese Laid-Open Patent Publication No. 2006-216491 (hereinafter referred to as the prior art), an anode side plate (separator) includes a fuel gas supply manifold forming section 1a, a fuel gas discharge manifold forming section 1b, an oxygen-containing gas supply manifold forming section 2a, an oxygen-containing gas discharge manifold forming section 2b, a coolant supply manifold forming section 3a, and a coolant discharge manifold forming section 3b. 
Further, the anode side plate includes a plurality fuel gas supply holes 4a arranged in a line and on the center side of the fuel gas supply manifold forming section 1a, and a plurality of fuel gas discharge holes 4b arranged in a line and on the center side of the fuel gas discharge manifold forming section 1b. 
The anode side plate includes a corrugated power generation area which faces an MEA when components of the fuel cell are assembled together. The anode side plate has a fuel gas flow field forming section 5 on its surface facing the MEA, and a coolant flow field forming section 6 on its surface opposite to the surface where the fuel gas flow field forming section 5 is provided. Grooves of the coolant flow field forming section 6 and grooves of the fuel gas flow field forming section 5 are formed alternately in the vertical direction.